Browsing by Author "Coutts, Janelle"

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Biofilm Resistant Coatings for Space Applications
(48th International Conference on Environmental Systems, 2018-07-08) Li, Wenyan; Hummerick, Mary; Khodadad, Christina; Buhrow, Jerry; Spencer, Lashelle; Coutts, Janelle; Roberson, Luke; Tuteja, Anish; Mehta, Geeta; Boban, Mathew; Barden, Michael
Bacterial biofilms are an important and often problematic aspect of life on earth and in space. Microbial contamination onboard the International Space Station (ISS) continues to pose mission risks, both to crew health and hardware reliability. In order to optimize the design of the future space exploration vehicle for long term missions, new technologies are needed to control the habitat’s microbial environment over multiple years. Among the emerging technologies for combating biofilm, new surface coatings show promise for preventing biofilm formation. This approach aims to interrupt the critical initial step of biofilm formation (cell attachment) through surface modification. When successfully developed, biofilm resistant coatings can eliminate/reduce the need for disinfectants, and avoid the development of “superbugs,” thus offering distinctive advantages for biofilm prevention during long term missions. Initial results at KSC showed that omniphobic coatings are promising candidates as biofilm resistant materials. Parabolic flight experiments also verified their physical properties under microgravity.
Evaluation of Aquaporin Membranes Using ISS Humidity Condensate Ersatz Wastewater
(46th International Conference on Environmental Systems, 2016-07-10) Shaw, Hali; Flynn, Michael; Parodi, Jurek; Stefanson, Ofir; Andersen, Thomas; Vogel, Jörg; Beeler, David; Coutts, Janelle; Kayatin, Matthew
On the International Space Station (ISS), distillate from the Urine Processor Assembly (UPA) and humidity condensate from the cabin are processed through a sequence of operations including distillation, filtration, adsorption, ion exchange, and catalytic oxidation. The use of adsorption and ion exchange beds in the Water Processor Assembly (WPA) are one of the main contributors to the resupply mass requirement. Developing improvements to the multifiltration system in order to reduce or eliminate the usage rate of expendable media such as adsorbents and ion-exchange resins is an important part of the evolution of ISS systems for future exploration missions. Development of the ISS Multifiltration Bed Replacement (MFBR) technology is based on a new generation of biomimetic membranes derive their unique characteristics from a protein call an Aquaporin. These membranes are capable of rejecting many semi-volatile organic compounds and were recently commercialized by the company Aquaporin A/S. NASA has conducted several studies on the use of Aquaporin membranes for the rejection of total organic carbon (TOC) of simulated ISS humidity condensate wastewater. Tests were conducted to determine the maximum water recovery ratio, and TOC rejection for both a flat sheet membrane and a membrane module. The results indicate that the aquaporin membrane can reject a minimum of 50% of the TOC using the simulated ISS humidity condensate ersatz, and achieves product water with a TOC value below 30 ppm.
Hollow Fiber Membrane Bioreactor Systems for Wastewater Processing: Effects of Environmental Stresses Including Dormancy Cycling and Antibiotic Dosing
(46th International Conference on Environmental Systems, 2016-07-10) Coutts, Janelle; Hummerick, Mary; Lunn, Griffin M.; Larson, Brian; Spencer, Lashelle; Kosiba, Michael; Khodadad, Christina; Catechis, John
Hollow fiber membrane bioreactors (HFMBs) have been studied for a number of years as an alternate approach for treating wastewater streams during space exploration. While the technology provides a promising pre-treatment for lowering organic carbon and nitrogen content without the need for harsh stabilization chemicals, several challenges must be addressed before adoption of the technology in future missions. One challenge is the transportation of bioreactors containing intact, active biofilms as a means for rapid start-up on the International Space Station or beyond. Similarly, there could be a need for placing these biological systems into a dormant state for extended periods when the system is not in use, along with the ability for rapid restart. Previous studies indicated that there was little influence of storage condition (4 or 25ºC, with or without bulk fluid) on recovery of bioreactors with immature biofilms (48 days old), but that an extensive recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy within 4 days (~1 residence). Further dormancy and recovery testing is presented here that examines the role of biofilm age on recovery requirements, repeated dormancy cycle capabilities, and effects of long-duration dormancy cycles (8-9 months) on HFMB systems. Another challenge that must be addressed is the possibility of antibiotics entering the wastewater stream. Currently, for most laboratory tests of biological water processors, donors providing urine may not contribute to the study when taking antibiotics because the effects on the system are yet uncharacterized. A simulated urinary tract infection event, where an opportunistic, pathogenic organism, E. coli, was introduced to the HFMBs followed by dosing with an antibiotic, ciprofloxacin, was completed to study the effect of the antibiotic on reactor performance and to also examine the development of antibiotic-resistant communities within the system.
Visible-Light-Responsive Photocatalysis: Ag-Doped TiO2 Catalyst Development and Reactor Design Testing
(46th International Conference on Environmental Systems, 2016-07-10) Coutts, Janelle; Hintze, Paul; Meier, Anne; Devor, Robert; Surma, Jan; Maloney, Phillip; Bauer, Brint; Shah, Malay; Mazyck, David
In recent years, the alteration of titanium dioxide to become visible-light-responsive (VLR) has been a major focus in the field of photocatalysis. Currently, bare titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Hg-vapor fluorescent light sources are used in photocatalytic oxidation (PCO) reactors to provide adequate levels of ultraviolet light for catalyst activation; these mercury-containing lamps, however, hinder the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. VLR-TiO2 would allow for use of ambient visible solar radiation or highly efficient visible wavelength LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Over the past three years, Kennedy Space Center has developed a VLR Ag-doped TiO2 catalyst with a band gap of 2.72 eV and promising photocatalytic activity. Catalyst immobilization techniques, including incorporation of the catalyst into a sorbent material, were examined. Extensive modeling of a reactor test bed mimicking air duct work with throughput similar to that seen on the International Space Station was completed to determine optimal reactor design. A bench-scale reactor with the novel catalyst and high-efficiency blue LEDs was challenged with several common volatile organic compounds (VOCs) found in ISS cabin air to evaluate the system’s ability to perform high-throughput trace contaminant removal. The ultimate goal for this testing was to determine if the unit would be useful pre-heat exchanger operations to lessen condensed VOCs in recovered water and lowering the burden of VOC removal for water purification systems.